Differences

This shows you the differences between two versions of the page.

--- ffmpeg [2021/05/22 16:54] – [Converting] flac > mp3 rjt
+++ ffmpeg [2025/04/14 16:40] (current) – more info on 'copy' ... mb don't need to bang on so much ... rjt
@@ Line 1: / Line 1: @@
 ====== FFmpeg ======
+Super handy [[terminal_emulator|terminal]]-based tool for working with video.
 ===== Use =====
@@ Line 7: / Line 9: @@
 Most of the time I just use---
-<code>ffmpeg -i input.ext output.ext</code>
+<code>ffmpeg -i [input.ext] [output.ext]</code>
 ---and it usually works fine leaving it to just use defaults.
+This gives good results (and a smaller file size) converting MP3 to OGG though:
+<code>ffmpeg -i [input].mp3 -c:a libvorbis -q:a 4 [output].ogg</code>
+Fuck-off those .WEBMs. ''copy'' here copies those streams, so they're no reencoded, it's just changing the container:
+<code>ffmpeg -i [input].webm -acodec copy -vcodec copy [output].mkv</code>
+A more compact way is to use ''-c'', which will copy over all streams (there's also ''-c:a'' (audio) ''-c:v'' (video) ''-c:s'' (subtitles)…:
+<code>ffmpeg -i [input].webm -c copy [output].mkv</code>
+So if you wanted to copy the video stream and just reencode/change the audio, for example:
+<code>ffmpeg -i [input].[ext] -acodec aac -vcodec copy [output].[ext]</code>
 === Multiple ===
@@ Line 15: / Line 33: @@
 For doing a whole directory I use this one-liner I got from Stack Exchange.
-<code>for i in *.ext; do ffmpeg -i "$i" "${i%.*}.ext"; done</code>
+<code>for i in *.[ext]; do ffmpeg -i "$i" "${i%.*}.[ext]"; done</code>
+For converting files for my [[m-u-s-u-c]] blog I also strip out the cover images: ''-map a'' tells it to take only the audio stream.
+<code>for i in *.mp3; do ffmpeg -i "$i" -c:a libvorbis -q:a 4 -map a "${i%.*}.ogg"; done</code>
-You can use the wildcard ''*'' in the file extension to, so if you've got a mix of .mkv and .mp4 files from Youtube you can do. say:
+You can use the wildcard ''*'' in the file extension too, so if you've got a mix of .mkv and .mp4 files from Youtube you can do. say:
 <code>for i in *.m*; do ffmpeg -i "$i" "${i%.*}.ogv"; done</code>
@@ Line 23: / Line 45: @@
 If you want to put the new videos into a subdirectory, first create it, then simply add it to the output part:
-<code>for i in *.ext; do ffmpeg -i "$i" "directory/${i%.*}.ext"; done</code>
+<code>for i in *.[ext]; do ffmpeg -i "$i" "directory/${i%.*}.[ext]"; done</code>
-For converting a directory of .FLAC files to .MP3. ''[-qscale:a 0|-b:a 320k]'' is your choice between VBR with the best quality (0) or a CBR of 320k. VBR is generally just as good, though sometimes you need CBR.
+For converting a directory of .FLAC files to .MP3. ''[-q:a 0|-b:a 320k]'' is your choice between VBR with the best quality (0) or a CBR of 320k. VBR is generally just as good, though sometimes you need CBR.
+<code>for i in *.flac; do ffmpeg -i "$i" [-q:a 0|-b:a 320k] "${i%*}.mp3"; done</code>
-<code>for a in ./*.flac; do ffmpeg -i "$a" [-qscale:a 0|-b:a 320k] "${a[@]/%flac/mp3}"; done</code>
 ==== Editing ====
 === Concatenation ===
@@ Line 38: / Line 61: @@
 <code>ffmpeg -f concat -safe 0 -i "inputfile.txt" -c copy "inputfile.ext"</code>
-nbjp Todo: use bash to generate the file list
+[[https://trac.ffmpeg.org/wiki/Concatenate#demuxer|FFmpeg's docs on generating the list]]:
+<code>
+# with a bash for loop
+for f in *.wav; do echo "file '$f'" >> mylist.txt; done
+# or with printf
+printf "file '%s'\n" *.wav > mylist.txt
+</code>
+If you have a movie in two parts and want to stick them together with less fuss, or you just want to save yourself the trouble of making the file, you can use //process substitution//:
+<code>ffmpeg -f concat -safe 0 -i <(for f in ./*.avi; do echo "file '$PWD/$f'"; done) -c copy output.avi</code>
+NB: Some older codecs let you stick files together with just [[cat]]!: https://ffmpeg.org/faq.html#toc-Concatenating-using-the-concat-protocol-_0028file-level_0029
+=== Cropping ===
+To crop a 16:9 video to 4:3, add:
+<code>-filter:v "crop=ih/3*4:ih"</code>
+Full example, with copied audio stream:
+<code>ffmpeg -i [file] -filter:v "crop=ih/3*4:ih" -c:a copy [file]</code>
 === Remove Audio ===
@@ Line 49: / Line 95: @@
 === Trimming ===
-You can pretty easily make a video file smaller. The only caveat is that if you don't want to re-encode you're limited by where keyframes are placed.
+You can pretty easily make a video shorter. The only caveat is that if you don't want to re-encode you're limited by where keyframes are placed.
 <code>ffmpeg -i inputfile.ext -ss HH:MM:SS -to HH:MM:SS -c copy outputfile.ext</code>
@@ Line 61: / Line 107: @@
   * If you leave out the ''-c copy'' it will re-encode the video
+==== Images ====
+=== Extract each frame as an image ===
+<code>ffmpeg -i [file] frame%03d.png</code>
+=== Create video from images ===
+<code>cat *.png | ffmpeg -framerate [framerate] -f image2pipe -i - [file]</code>
+== GIF ==
+Default loops. Add ''-loop -1'' to only play once.
+<code>cat *.png | ffmpeg -framerate [framerate] -f image2pipe -i - [filename].gif</code>
+== APNG ==
+Default doesn't loop. Add ''-plays 0'' to loop.
+<code>cat *.png | ffmpeg -framerate [framerate] -f image2pipe -i - -f apng [filename].png</code>
 ==== Lowering the file size ====
 Slow, but compresses better:
@@ Line 75: / Line 137: @@
   * https://trac.ffmpeg.org/wiki/Scaling
+==== Repairing ====
+Just had an .AVI file throwing error messages about a busted index. Copying the file seemed to fix it.
+<code>ffmpeg -i "inputfile.avi" -c:v copy -c:a copy "outputfile.avi"</code>
+===== Frontends =====
+  * [[https://ffmpeg.lav.io/|FFmpeg Explorer]] - Browser-based GUI with a node-based interface for changing parameters.
 ===== See Also =====
   * [[https://www.ffmpeg.org/|www.ffmpeg.org]]
+  * [[https://trac.ffmpeg.org/wiki|FFmpeg Bug Tracker and Wiki]]
+  * [[gifsicle]] - Similar tool, specifically for working with [[gif|GIFs]]
 {{tag>CLI guide software tool video}}